Contactless power transmitting system having overheat protection function and method thereof

ABSTRACT

Disclosed herein are a contactless power transmitting system having an overheat protection function, which protects a battery cell module from damage due to overheating while the battery cell module is being charged, and a method thereof. In the contactless power transmitting system, a contactless power transmitting apparatus transmits a first power to a contactless power receiving apparatus through a power transmitting coil to charge the battery cell module with the first power, and transmits a second power, of lower wattage than the first power, to the contactless power receiving apparatus through the power transmitting coil to charge the battery cell module with the second power if an overheat alarm signal is received from the contactless power receiving apparatus, thereby making it possible to fully charge the battery cell module while preventing overheating of the battery cell module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/667,615, filed Nov. 2, 2012, which claims the benefit of KoreanApplication No. 10-2011-0113239, filed Nov. 2, 2011 in the KoreanIntellectual Property Office and entitled “Contactless PowerTransmitting System Having Overheat Protection Function And MethodThereof”, the disclosure of which is incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a contactless power transmitting systemhaving an overheat protection function, which protects a battery cellmodule from damage due to overheating while the battery cell module isbeing charged, and a method thereof.

2. Description of the Related Art

Generally, a portable terminal such as a cellular phone, a personaldigital assistant (PDA), or the like, includes a battery pack. Thebattery pack may be charged with a power supplied from an externalcharging apparatus, and may supply the charged power to the portableterminal for operation according to a manipulation of a user.

The battery pack may include a battery cell module charged with thepower, and a circuit for charging and discharging the power in thebattery cell module, among other components.

One method of electrically connecting the battery pack and the chargingapparatus to each other is a direct contact between a terminal of thecharging apparatus and a terminal of the battery pack.

However, when the two terminals contact each other or are separated fromeach other, because the terminal of the battery pack and the terminal ofthe charging apparatus have different potential differences, aninstantaneous discharge phenomenon can occur. This instantaneousdischarge phenomenon causes abrasion of the terminals, and creates arisk of an accident such as a fire or the like if foreign materials haveaccumulated in either terminal.

In addition, the electrical energy charged in the battery pack naturallydischarges into the environment through the terminal of the battery packdue to moisture or the like, such that a lifespan of the battery packmay decrease and performance thereof may deteriorate.

Recently, contactless power transmitting systems, using methods oftransmitting a power without a direct contact between terminals, havebeen suggested in order to solve several problems of the terminalconnection method as described above.

In these contactless power transmitting systems, efforts to improvetransmission efficiency of the power, as well as to stably transmit andreceive the power, have been made.

SUMMARY OF THE INVENTION

While not limited thereto, according to an embodiment of the presentinvention, when a contactless power receiving apparatus receives a firstpower transmitted by a contactless power transmitting apparatus and acharging apparatus charges a battery cell module with the first power,the contactless power receiving apparatus may judge whether or not thebattery cell module has been overheated.

According to an aspect of the invention, the judging of whether or notthe battery cell module has been overheated may be performed bydetecting a first temperature of the battery cell module using a firsttemperature sensor, and judging that the battery cell module has beenoverheated if the detected first temperature is equal to or higher thana preset temperature.

According to an aspect of the invention, the judging of whether or notthe battery cell module has been overheated may be performed bydetecting a first temperature of the battery cell module using a firsttemperature sensor, detecting a second temperature of the environmentusing a second temperature sensor, and judging that the battery cellmodule has been overheated if a difference between the first temperatureand the second temperature is equal to or higher than a presetdifference in temperature.

According to an aspect of the invention, if it is judged that thebattery cell module has been overheated, the contactless power receivingapparatus may generate an overheat alarm signal to transmit to thecontactless power transmitting apparatus.

According to an aspect of the invention, the contactless powertransmitting apparatus may transmit a second power, of lower wattagethan the first power, to the contactless power receiving apparatus, ifthe overheat alarm signal is received, to charge the battery cell modulewith the second power, thereby preventing the battery cell module fromoverheating.

According to an aspect of the invention, after the contactless powerreceiving apparatus generates the overheat alarm signal, the chargingunit may switch to a second power charging mode in which the batterycell module is charged with the second power, thereby preventinggeneration of an error.

While not limited thereto, according to an embodiment of the presentinvention, a contactless power transmitting apparatus having an overheatprotection function may comprise a power transmitting unit, comprising apower transmitting coil which transmits a power to a contactless powerreceiving apparatus; a first signal receiving unit which receives anoverheat alarm signal transmitted by the contactless power receivingapparatus; and a contactless power transmission controlling unit whichdirects the power transmitting unit to transmit a first power to thecontactless power receiving apparatus, and which directs the powertransmitting unit to transmit a second power, of lower wattage than thefirst power, to the contactless power receiving apparatus if the firstsignal receiving unit receives the overheat alarm signal.

According to an aspect of the invention, the power transmitting unit mayfurther comprise a driving driver which generates a driving signal fortransmitting the first power or the second power under a direction ofthe contactless power transmission controlling unit; and a seriesresonant converter which switches a direct current (DC) power accordingto the driving signal, wherein the power transmitting coil transmits thefirst power or the second power to the contactless power receivingapparatus while being resonated with the power switched by the seriesresonant converter.

According to an aspect of the invention, the contactless powertransmitting apparatus may further comprise a first signal transmittingunit which generates an identification (ID) request signal and transmitsthe generated ID request signal to the contactless power receivingapparatus, under a direction of the contactless power transmissioncontrolling unit, wherein the first signal receiving unit receives an IDsignal transmitted by the contactless power receiving apparatusaccording to the ID request signal and provides the received ID signalto the contactless power transmission controlling unit.

While not limited thereto, according to an embodiment of the presentinvention, a contactless power receiving apparatus having an overheatprotection function may a charging apparatus which receives a firstpower transmitted by a contactless power transmitting apparatus, andwhich charges a battery cell module with the first power; a secondsignal transmitting unit which generates an overheat alarm signal, andwhich transmits the overheat alarm signal to the contactless powertransmitting apparatus; and a contactless power reception controllingunit which judges whether or not the battery cell module has beenoverheated, and which, if it is judged that the battery cell module hasbeen overheated, directs the second signal transmitting unit to generatethe overheat alarm signal and transmit the generated overheat alarmsignal to the contactless power transmitting apparatus and then directsthe charging apparatus to receive a second power, of lower wattage thanthe first power, from the contactless power transmitting apparatus andto charge the battery cell module with the second power.

According to an aspect of the invention, the contactless power receivingapparatus may further comprise a first temperature sensor which detectsa first temperature of the battery cell module, wherein the contactlesspower reception controlling unit judges whether or not the battery cellmodule has been overheated using the first temperature.

According to an aspect of the invention, the contactless power receivingapparatus may further comprise a first temperature sensor which detectsa first temperature of the battery cell module; and a second temperaturesensor which detects a second temperature of the environment, whereinthe contactless power reception controlling unit judges whether or notthe battery cell module has been overheated using a difference betweenthe first and second temperatures.

According to an aspect of the invention, the contactless power receivingapparatus may further comprise a second signal receiving unit whichreceives an ID request signal transmitted by the contactless powertransmitting apparatus, and which provides the ID request signal to thecontactless power reception controlling unit, wherein, if the ID requestsignal is received, the second signal transmitting unit generates an IDsignal and transmits the generated ID request signal to the contactlesspower transmitting apparatus under a direction of the contactless powerreception controlling unit.

According to an aspect of the invention, the charging apparatus maycomprise a power receiving coil which receives the first power or thesecond power transmitted by the contactless power transmittingapparatus; a rectifying unit which rectifies the first power or thesecond power received by the power receiving coil into a DC power; and acharging unit which charges the battery cell module with the DC powerrectified by the rectifying unit, under a direction of the contactlesspower reception controlling unit.

While not limited thereto, according to an embodiment of the presentinvention, a contactless power receiving method having an overheatprotection function may comprise transmitting, using a contactless powertransmitting apparatus, a first power to a contactless power receivingapparatus through a power transmitting coil; and transmitting, using thecontactless power transmitting apparatus, a second power, of lowerwattage than the first power, to the contactless power receivingapparatus through the power transmitting coil if an overheat alarmsignal is received from the contactless power receiving apparatus.

According to an aspect of the invention, the transmitting of the firstpower may comprise transmitting, using the contactless powertransmitting apparatus, an ID request signal to the contactless powerreceiving apparatus; and transmitting the first power if an ID signal isreceived from the contactless power receiving apparatus according to theID request signal.

According to an aspect of the invention, the transmitting of the IDrequest signal may comprise judging whether or not a change in a loadhas been generated in the power transmitting coil; and transmitting theID request signal if it is judged that the change in the load has beengenerated in the power transmitting coil.

According to an aspect of the invention, the contactless powertransmitting method may further comprise stopping the transmission ofthe first or second power if a charge completion signal is received fromthe contactless power receiving apparatus.

While not limited thereto, according to an embodiment of the presentinvention, a contactless power transmitting method having an overheatprotection function may comprise receiving, in a charging apparatus, afirst power transmitted by a contactless power transmitting apparatus tocharge a battery cell module with the first power; judging, using acontactless power reception controlling unit, whether or not the batterycell module has been overheated; if it is judged that the battery cellmodule has been overheated, transmitting an overheat alarm signal to thecontactless power transmitting apparatus; and if the overheat alarmsignal is transmitted, receiving, in the charging apparatus, a secondpower, of lower wattage than the first power, to charge the battery cellmodule with the second power.

According to an aspect of the invention, the judging of whether or notthe battery cell module has been overheated may comprise detecting, in afirst temperature sensor, a first temperature of the battery cellmodule; and judging that the battery cell module has been overheated ifthe first temperature is equal to or higher than a preset temperature.

According to an aspect of the invention, the judging of whether or notthe battery cell module has been overheated may comprise detecting, in afirst temperature sensor, a first temperature of the battery cellmodule; detecting, in a second temperature sensor, a second temperatureof the environment; and judging that the battery cell module has beenoverheated if a difference between the first and second temperatures isequal to or higher than a preset value.

According to an aspect of the invention, the contactless power receivingmethod may further comprise judging, in the contactless power receptioncontrolling unit, whether or not the charging of the battery cell modulehas been completed; and, if it is judged that the charging of thebattery cell module has been completed, transmitting a charge completionsignal to the contactless power transmitting apparatus.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a diagram of a configuration of a contactless powertransmitting system according to an embodiment of the present invention;

FIG. 2 is a signal flow chart showing operations of a contactless powertransmission controlling unit in a method according to an embodiment ofthe present invention; and

FIG. 3 is a signal flow chart showing operations of a contactless powerreception controlling unit in a method according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures, and to present aprinciple and a concept of the present invention in a manner that mostusefully and easily described the present invention.

The following detailed description is only an example and onlyillustrates exemplary embodiments of the present invention. For basicunderstanding of the present invention, unnecessary details andadditional embodiments of the present invention that may be executed bythose skilled in the art will not be described.

According to an aspect of the invention depicted in FIG. 1, acontactless power transmitting system may comprise a contactless powertransmitting apparatus 100 and a contactless power receiving apparatus200.

The contactless power transmitting apparatus 100 transmits a power usinga method of electromagnetic induction, and the contactless powerreceiving apparatus 200 receives the power using the method ofelectromagnetic induction. More specifically, the contactless powertransmitting apparatus 100 transmits a first power, or a second power oflower wattage than the first power, without a direct contact. Thecontactless power receiving apparatus 200 receives the transmitted firstpower or second power, for use to charge a battery cell module 250 or tosupply an operation power to a load such as a portable terminal or thelike; said load may be the contactless power receiving apparatus 200itself.

The contactless power transmitting apparatus 100 is operated by a directcurrent (DC) power supplied by an alternate current (AC) to DC converter(not shown). The AC to DC converter may be provided separately from orintegrally with the contactless power transmitting apparatus 100.

The contactless power transmitting apparatus 100 may comprise acontactless power transmission controlling unit 110, a powertransmitting unit, a first signal transmitting unit 150, and a firstsignal receiving unit 160.

The contactless power transmission controlling unit 110 recognizes thecontactless power receiving apparatus 200 and directs a transmission ofthe first power or the second power.

The power transmitting unit, which transmits the first power or thesecond power to the contactless power receiving apparatus 200 under thedirection of the contactless power transmission controlling unit 110,may include a driving driver 120, a series resonant converter 130, and apower transmitting coil 140.

The driving driver 120 generates one or more driving signals under thecontrol of the contactless power transmission controlling unit 110. Saiddriving signals may include but are not limited to a signal to detect achange in a load, a signal to transmit the first power, a signal totransmit the second power, and so forth.

The series resonant converter 130 switches a DC power, supplied from theAC to DC converter or the like, according to the driving signalsgenerated by the driving driver 120. The serial resonant converter 130may comprise switching devices such as a plurality of transistors, andmore specifically a plurality of metal oxide semiconductor field effecttransistors (MOSFETs); however, numerous other compositions andarrangements may be appreciated by those of skill in the art.

The power transmitting coil 140 of the power transmitting unit generatesa signal to detect a change in the load while being resonated in serieswith the power switched by the series resonant converter 130, andtransmits the first power or the second power.

Although the depiction in FIG. 1 shows only one power transmitting coil140, a plurality of power transmitting coils may be connected and usedin parallel with each other in practicing the present invention. In thecase of using the plurality of power transmitting coils, a switch and acapacitor may be provided in series with each of the plurality of powertransmitting coils, and the switch may be selectively switched under thecontrol of the contactless power transmission controlling unit 110 toallow the power switched in the series resonant converter 130 to beselectively outputted to the plurality of power transmitting coils.Specific systems and methods of connecting a plurality of powertransmitting coils are well known in the art, and those skilled in theart will recognize ways to incorporate said systems and methods intoaspects of the present invention.

The first signal transmitting unit 150 generates an identification (ID)request signal or the like under the direction of the contactless powertransmission controlling unit 110, and provides said signal to the powertransmitting coil 140 to be transmitted to the contactless powerreceiving apparatus 200.

The first signal receiving unit 160 receives one or more signals, andmay provide said signals to the contactless power transmissioncontrolling unit 110. Said signals may include but are not limited to asignal indicating a change in a load of the power transmitting coil 140,an ID signal transmitted by the contactless power receiving apparatus200, an overheat alarm signal, a charging completion signal, and soforth.

The contactless power receiving apparatus 200 may comprise a contactlesspower reception controlling unit 210, a charging apparatus, a batterycell module 250, a second signal receiving unit 260, a first temperaturesensor 270, a second temperature sensor 280, a second signaltransmitting unit 290, and the like.

The contactless power reception controlling unit 210 directs atransmission of an ID signal to the contactless power transmittingapparatus 100, according to the ID request signal transmitted by thecontactless power transmitting apparatus 100; directs a reception of thefirst power or the second power transmitted by the contactless powertransmitting apparatus 100 to charge the battery cell module 250; anddirects a generation of an overheat alarm signal if the battery cellmodule 250 is overheated, said signal then being transmitted to thecontactless power transmitting apparatus 100.

The charging apparatus, which receives the first power or the secondpower transmitted by the contactless power transmitting apparatus 100 tocharge the battery cell module 250 under the direction of thecontactless power reception controlling unit 210, may include a powerreceiving coil 220, a rectifying unit 230, and a charging unit 240.

The power receiving coil 220 is coupled to the power transmitting coil140 of the contactless power transmitting apparatus 100, usingelectromagnetic induction to receive the first power or the second powertransmitted by the contactless power transmitting apparatus 100.

The rectifying unit 230 rectifies the first power or the second power,received by the power receiving coil 220, into a DC power.

The charging unit 240 charges the battery cell module 250 using the DCpower rectified by the rectifying unit 230, under the direction of thecontactless power reception controlling unit 210.

The second signal receiving unit 260 receives the ID request signal orthe like transmitted by the contactless power transmitting apparatus 100through the power receiving coil 220, and provides said signal to thecontactless power reception controlling unit 210.

The first temperature sensor 270 detects a first temperature of thebattery cell module 250 and provides the detected first temperature tothe contactless power reception controlling unit 210.

The second temperature sensor 280 detects a second temperature of theenvironment and provides the detected second temperature to thecontactless power reception controlling unit 210.

The second signal transmitting unit 290 generates one or more signalsand transmits them to the contactless power transmitting apparatus 100through the power receiving coil 220. These one or more signals mayinclude but are not limited to the ID signal, the overheat alarm signal,the charge completion signal, and so forth.

FIG. 2 is a signal flow chart showing operations of a contactless powertransmission controlling unit 110 of a contactless power transmittingapparatus 100, according to an embodiment of the present invention.

In the embodiment depicted in FIG. 2, the contactless power transmittingapparatus 100 judges whether or not the contactless power receivingapparatus 200 may receive a power transmitted by the contactless powertransmitting apparatus 100 and, if so, transmits the power to thecontactless power receiving apparatus 200. In at least one embodiment,this judgment may be based on whether or not the power receiving coil220 of the contactless power receiving apparatus 200 has approached thepower transmitting coil 140 included in the contactless powertransmitting apparatus 100.

To this end, the contactless power transmission controlling unit 110 ofthe contactless power transmitting apparatus 100 directs the drivingdriver 120 to generate a driving signal for detecting the change in theload (S100).

The driving signal is generated by the driving driver 120 and providedto the serial resonant converter 130.

The serial resonant converter 130 selectively switches a plurality ofswitching devices, according to the driving signal, to switch a DCpower, thereby generating an AC power and outputting the generated ACpower to the power transmitting coil 140, such that serial resonance isgenerated in the power transmitting coil 140.

Here, the first signal receiving unit 160 receives the signal of thepower transmitting coil 140 and provides the received signal to thecontactless power transmission controlling unit 110.

The contactless power transmission controlling unit 110 is provided withthe signal of the first signal receiving unit 160 and judges whether ornot a change in the load has been generated in the power transmittingcoil 140 using the provided signal (S102).

That is, if the power receiving coil 220 of the contactless powerreceiving apparatus 200 does not approach the power transmitting coil140, a change in impedance is not generated in the power transmittingcoil 140.

In at least one embodiment, the first signal receiving unit 160 mayreceive a frequency signal according to the driving signal generated bythe driving driver 120, and the contactless power transmissioncontrolling unit 110 may judge, using said signal, that a change in theload has not been generated in the power transmitting coil 140.

In addition, when the power receiving coil 220 of the contactless powerreceiving apparatus 200 approaches the power transmitting coil 140 inorder to charge the battery pack module 240 of the contactless powerreceiving apparatus 200, a change in impedance is generated in the powertransmitting coil 140, and the frequency signal is changed according tothe generated change in the impedance.

Therefore, the first signal receiving unit 160 receives the signal witha frequency changed according to the change in the impedance, and thecontactless power transmission controlling unit 110 judges that a changein the load has been generated in the power transmitting coil 140 usingthe signal of the first signal receiving unit 160.

If it is judged in operation (S102) that a change in the load had notbeen generated, the contactless power transmission controlling unit 110returns to operation (S100) to repeatedly direct the driving driver 120to generate the driving signal for detecting a change in the load.

If it is judged in operation (S102) that a change in the load has beengenerated, the contactless power transmission controlling unit 110directs the first signal transmitting unit 150 to generate an ID requestsignal, requesting the ID of the contactless power receiving apparatus200, and transmits said signal to the contactless power receivingapparatus 200 through the power transmitting coil 140 (S104).

A change in the impedance may be generated in the power transmittingcoil 140 not only when the power receiving coil 220 of the contactlesspower receiving apparatus 200 approaches the power transmitting coil 140as described above, but even when foreign materials other than thecontactless power receiving apparatus 200 approach the powertransmitting coil 140. If the impedance is generated by foreignmaterials, then should the contactless power transmitting apparatus 100transmit a power, a large amount of power would be unnecessarilyconsumed.

Therefore, while this operation may be excluded without departure fromthe scope of the present invention, in at least one embodiment, thecontactless power transmission controlling unit 110 is provided with thesignal of the first signal receiving unit 160 to judge whether or notthe ID signal has been received from the contactless power receivingapparatus 200 (S106).

The contactless power transmission controlling unit 110 transmits the IDrequest signal to the contactless power receiving apparatus 200 if it isjudged that the change in the load has been generated in the powertransmitting coil 140, and judges whether the impedance of the powertransmitting coil 140 has been changed by the contactless powerreceiving apparatus 200, based on whether the ID signal is received fromthe contactless power receiving apparatus 200 according to the IDrequest signal.

If it is judged in operation (S106) that the ID signal has not beenreceived, the contactless power transmission controlling unit 110 judgeswhether or not a preset time has elapsed (S108), and returns tooperation (S106) if it is judged that the preset time has not elapsed,thereby repeatedly judging whether or not the ID signal has beenreceived from the contactless power receiving apparatus 200.

If the ID signal is not received from the contactless power receivingapparatus 200 and the preset time has elapsed, the contactless powertransmission controlling unit 110 returns to operation (S100) torepeatedly instruct the driving driver 120 to generate the drivingsignal for detecting the change in the load.

On the other hand, if the ID signal is received before the preset timeelapses, the contactless power transmission controlling unit 110 judgesthat the power receiving coil 220 of the contactless power receivingapparatus 200 has approached the power transmitting coil 140, anddirects the driving driver 120 to generate the driving signal fortransmitting the first power (S110).

The switching devices of the series resonant converter 130 are switchedaccording to the driving signal for transmitting the first power,generated by the driving driver 120, to switch the DC power and applythe switched power to the power transmitting coil 140, such that thefirst power is transmitted from the power transmitting coil 140 to thepower receiving coil 220 of the contactless power receiving apparatus200.

Here, the contactless power transmission controlling unit 110 isprovided with the signal of the first signal receiving unit 160 to judgewhether or not an overheat alarm signal has been received from thecontactless power receiving apparatus 200 (S112), and judges whether ornot a charge completion signal has been received from the contactlesspower receiving apparatus 200 (S114) if it is judged that the overheatalarm signal has not been received.

If it is judged that the charge completion signal has been received fromthe contactless power receiving apparatus 200, the contactless powertransmission controlling unit 110 ends the power transmission.

However, if the overheat alarm signal is received before the chargecompletion signal is received from the contactless power receivingapparatus 200, the contactless power transmission controlling unit 110directs the driving driver 120 to generate a driving signal fortransmitting a second power of lower wattage than the first power(S116).

In this case, the switching devices of the series resonant converter 130are switched according to the driving signal for transmitting the secondpower, generated by the driving driver 120, such that the second poweris transmitted from the power transmitting coil 140 to the powerreceiving coil 220.

Here, the contactless power transmission controlling unit 110 isprovided with the signal of the first signal receiving unit 160 to judgewhether or not the charge completion signal has been received from thecontactless power receiving apparatus 200 (S118).

If it is judged that the charge completion signal has not been received,the contactless power transmission controlling unit 110 returns tooperation (S116) to repeatedly instruct the driving driver 120 togenerate the driving signal for the second power, and to judge whetheror not the charge completion signal has been received from thecontactless power receiving apparatus 200, ending the power transmissionif the charge completion signal is received.

FIG. 3 is a signal flow chart showing operations of a contactless powerreception controlling unit 210 in a method, according to an embodimentof the present invention.

In the embodiment depicted in FIG. 3, the contactless power receptioncontrolling unit 210 judges whether or not the ID request signal hasbeen received from the contactless power transmitting apparatus 100(S200).

That is, the ID request signal, which the contactless power transmissioncontrolling unit 110 of the contactless power transmitting apparatus 100directs the first signal transmitting unit 150 to transmit in operation(S104), is induced from the power transmitting coil 140 to the powerreceiving coil 220. The second signal receiving unit 260 then receivesthe induced ID request signal and provides said signal to thecontactless power reception controlling unit 210, and the contactlesspower reception controlling unit 210 judges whether or not the IDrequest signal has been received.

When the ID request signal is received from the contactless powertransmitting apparatus 100, the contactless power reception controllingunit 210 directs the second signal transmitting unit 290 to generate anID signal and transmit said signal to the contactless power transmittingapparatus 100 through the power receiving coil 220 (S202).

The ID signal transmitted by the contactless power receiving apparatus200 is induced from the power receiving coil 220 to the powertransmitting coil 140 as described above, the first signal receivingunit 160 receives the ID signal and provides said signal to thecontactless power transmission controlling unit 110, and the contactlesspower transmission controlling unit 110 judges whether or not the IDsignal has been received in operation (S106).

Here, the first power transmitted by the contactless power transmittingapparatus 100 is induced to the power receiving coil 220, the rectifyingunit 230 rectifies the induced first power and provides the rectifiedfirst power to the charging unit 240, and the contactless powerreception controlling unit 210 monitors the charging unit 240 to judgewhether or not the first power has been received (S204).

If it is judged that the first power has been received, the contactlesspower reception controlling unit 210 directs the charging unit 240 tocharge the battery cell module 250 with the received first power (S206).

While the first power charges the battery cell module 250 as describedabove, the contactless power reception controlling unit 210 judgeswhether or not the battery cell module 250 has been overheated (S208).

Here, whether or not the battery cell module 250 has been overheated maybe judged by several methods according to various embodiments.

For example, the contactless power reception controlling unit 210 maydetect a first temperature of the battery cell module 250 using thefirst temperature sensor 270 and judge that the battery cell module 250has been overheated if the detected first temperature of the batterycell module 250 is equal to or higher than a preset temperature. In thiscase, the second temperature sensor 280 may not be necessary orprovided.

Alternatively to or in combination with the above method, thecontactless power reception controlling unit 210 may detect both saidfirst temperature of the battery cell module 250, using the firsttemperature sensor 270, and a second temperature of the environment,using a second temperature sensor 280, and judge that the battery cellmodule 250 has been overheated if the difference between the detectedfirst and second temperatures is equal to or higher than a presettemperature difference; for example, if the first temperature is higherthan the second temperature by 10° C. or more.

It will be recognized by those skilled in the art that still othermethods of detecting a state of overheating are possible withoutdeparting from the scope of the present invention.

If it is judged that the battery cell module 250 has not beenoverheated, the contactless power reception controlling unit 210monitors the charging unit 240 to judge whether or not the charging ofthe battery cell module 250 has been completed (S210).

Here, when it is judged that the charging of the battery cell module 250has been completed without overheating, the contactless power receptioncontrolling unit 210 directs the second signal transmitting unit 290 togenerate the charge completion signal and transmit said signal to thecontactless power transmitting apparatus 100 through the power receivingcoil 220 (S212).

The transmitted charge completion signal is induced to the powertransmitting coil 140 of the contactless power transmitting apparatus100 and is received by the first signal receiving unit 160 as describedabove, and the contactless power transmission controlling unit 110judges whether or not the charge completion signal has been received inoperation (S118).

However, if it is judged that the battery cell module 250 has beenoverheated before the charging of the battery cell module 250 iscompleted, the contactless power reception controlling unit 210 directsthe second signal transmitting unit 290 to generate an overheat alarmsignal and to transmit said signal to the contactless power transmittingapparatus 100 through the power receiving coil 220 (S214).

The transmitted overheat alarm signal is induced to the powertransmitting coil 140 and is received by the first signal receiving unit160. The contactless power transmission controlling unit 110 judgeswhether or not the overheat alarm signal has been received in operation(S112) and directs the driving driver 120 to generate the driving signalfor transmitting a second power, of lower wattage than the first power,if it is judged that the overheat alarm signal has been received,thereby allowing the second power to be transmitted, as described above.

Here, the contactless power reception controlling unit 210 directs thecharging unit 240 to be switched into a second power charging mode,thereby allowing the second power to charge the battery cell module 250(S216).

If the second power is provided to the charging unit 240 from therectifying unit 230, but the charging unit 240 remains in the firstpower charging mode, the charging unit 240 may judge that an error hasbeen generated. Therefore, while this function may be excluded withoutdeparture from the scope of the present invention, in at least oneembodiment, the contactless power reception controlling unit 210 bothgenerates the overheat alarm signal and switches the charging unit 240into the second power charging mode, thereby preventing the generationof an error by the charging unit.

While it is judged that the second power is charging the battery cellmodule 250 as described above, the contactless power receptioncontrolling unit 210 monitors the charging unit 240 to judge whether ornot the charging of the battery cell module 250 has been completed(S218).

If it is judged that the charging has not been completed, thecontactless power reception controlling unit 210 continues saidmonitoring of the charging unit 240.

If it is judged that the charging of the battery cell module 250 hasbeen completed, the contactless power reception controlling unit 210directs the second signal transmitting unit 290 to generate the chargecompletion signal and transmit said signal to the contactless powertransmitting apparatus 100 through the power receiving coil 220 (S220),and then ends the charging operation.

In summary, according to an embodiment of the present invention, whilethe contactless power transmitting apparatus transmits the first powerto the contactless power receiving apparatus to charge the battery cellmodule, whether or not the battery cell module has been overheated isjudged, and the contactless power transmitting apparatus transmits thesecond power, of lower wattage than the first power, to the contactlesspower receiving apparatus to charge the battery cell module if it isjudged that the battery cell module has been overheated. Therefore, itis possible to prevent the battery cell module from being overheated anddamaged, and to fully charge the battery cell module without risk ofdamage due to overheating.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents. Accordingly, the scope of the presentinvention is not construed as being limited to the describedembodiments.

What is claimed is:
 1. A wireless power transmitting method of awireless power transmitting apparatus in a system to wirelessly charge apower, the method comprising: detecting approach of a wireless powerreceiving apparatus based on a change in impedance of a powertransmitting coil, and verifying the wireless power receiving apparatus;wirelessly transmitting a first power to the wireless power receivingapparatus; and wirelessly transmitting a second power having a lowerpower level than the first power to the wireless power receivingapparatus when an overheat alarm signal is received from the wirelesspower receiving apparatus during a process of transmitting the firstpower to the wireless power receiving apparatus.
 2. The method of claim1, wherein the first power and the second power are transferred to apower receiving coil of the wireless power receiving apparatus through apower transmitting unit expressed as a circuit in which a coil and acapacitor are connected in series.
 3. The method of claim 1, wherein theverifying comprises receiving an identification signal of the wirelesspower receiving apparatus.
 4. The method of claim 1, wherein theverifying comprises: generating a driving signal for detecting thechange in the impedance of the power transmitting coil; and determiningwhether an identifier signal of the wireless power receiving apparatusis received within a predetermined period of time when the change in theimpedance of the power transmitting coil is detected, wherein thegenerating of the driving signal and the determining is repeatedlyperformed when the identifier signal is not received after thepredetermined period of time is elapsed.
 5. A wireless power receivingmethod of a wireless power receiving apparatus in a system to wirelesslycharge a power, the method comprising: generating a change in impedanceof a power transmitting coil and transmitting a message to a wirelesspower transmitting apparatus; wirelessly receiving a first power fromthe wireless power transmitting apparatus; determining whether thewireless power receiving apparatus is overheated during a process ofreceiving the first power, and transmitting an overheat alarm signal tothe wireless power transmitting apparatus when overheat of the wirelesspower receiving apparatus is detected; and receiving a second powerhaving a lower power level than the first power from the wireless powertransmitting apparatus.
 6. The method of claim 5, wherein the firstpower and the second power are received from a power transmitting unitof the wireless power transmitting apparatus expressed as a circuit inwhich a coil and a capacitor are connected in series.
 7. The method ofclaim 5, wherein the message comprises identifier information of thewireless power receiving apparatus.
 8. The method of claim 5, whereinthe transmitting a message to the wireless power transmitting apparatuscomprises: receiving an identification request signal from the wirelesspower transmitting apparatus when the change in the impedance of thepower transmitting coil is detected by the wireless power transmittingapparatus; and transmitting identification signal of the wireless powerreceiving apparatus to the wireless power transmitting apparatus.
 9. Themethod of claim 1, wherein the wireless power transmitting apparatusgenerate a signal periodically for detecting approach of the wirelesspower receiving apparatus.